Canyons are inherently risky. Flash floods occur without notice on sunny days. Technical skills & surrounding topography knowledge required yet does not eliminate risk.
Short but Sweet!
Among the major canyon cuts in the Alamogordo area there are also smaller, shorter drainages that do not cut all the way back into the ridges, but originate on the front of the formations. These typically cut up and back for just a few miles and at a glance would not be worth heading over to... but...
...you should take the time. For a simple day hike these provide some of the very best outings in the area. Black Rock is one of the shorter and more interesting of these day adventures. You begin your day at the trailhead for Alamo Canyon (T104) and hike south cross country to the third major drainage pouring off the escarpment. If you're lucky you'll encounter the old BLM road (powerline road) and follow it easily across the desert terrain. At some point you will need to leave that road and drop into one of the creek bottoms. Interestinly, they flow south along the face of the mountains and will carry you over to access any of the canyons. Black Rock is the last cut before you reach the major canyon: Mule Canyon.
The climbs are similar to what you'll find in Pock Rock Canyon, perhaps a bit more difficult. The major waterfalls can be skirted around, if needed. A bit over a mile up into the canyon the drainage splits. I have not hiked the left fork, but it appears to be a nice option for a traversing loop return: Hike up the right fork, then hike across to the head of the left fork and back down and around? Additionally, you can proceed up and out of the drainage, ascending the cliffs at the base of the Steamboat formation. It is possible to loop over and down into Alamo Canyon for a longer day.
The four hours noted is just for the one way portion of the hike... plan on a full day to go up and back!
These little canyons with their numberous pour over dry waterfalls provide some delightful full body workouts and some great moments of solitude and adventure. The approach to this one takes a bit more work, but it is well worth the effort.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.